I had the same problem so I made a fix:
change line 76 from this:
$footnoteContent = "<span id='easy-footnote-".$this->footnoteCount."' class='easy-footnote-margin-adjust'></span><span class='easy-footnote'><a href='".$footnoteLink."' title='$content'><sup>$this->footnoteCount</sup></a></span>";
to this:
$footnoteContent = "<span id='easy-footnote-".$this->footnoteCount."' class='easy-footnote-margin-adjust'></span><span class='easy-footnote'><a href='".$footnoteLink."' title='".htmlspecialchars($content, ENT_QUOTES)."'><sup>$this->footnoteCount</sup></a></span>";
hope it would help someone ??